Dicarboxylic acid esters of 2, 2, 4-trialkyl-3-hydroxypentyl alkanoates



United States Patent 3,414,609 DICARBOXYLIC ACID ESTERS 0F2,2,4-TRIALKYL- S-HYDROXYPENTYL ALKANOATES Hugh J. Hagemeyer, Jr., andAlfred G. Robinson, Longview, Tex., assiguors to Eastman Kodak Company,Rochester, N .Y., a corporation of New Jersey No Drawing.Continuation-impart of application Ser. No. 161,358, Dec. 22, 1961. Thisapplication Mar. 7, 1966, Ser. No. 532,053

7 Claims. (Cl. 260-475) This application is a continuation-in-part ofour copending application Ser. No. 161,358, filed Dec. 22, 1961, nowabandoned of the same title.

This invention relates to certain novel esters and to a novel catalyticmethod for preparing carboxylic acid esters of diol partial estershaving a free secondary hydroxyl group.

The invention is based on our discovery that diesters and polyestershaving unexpected valuable properties in a number of important uses canbe prepared from certain 2,2,4-trialkyl-3-hydroxypentyl alkanoates ofthe type:

i" R u R-CH-OH-C-CHrO-C-CH-R' wherein the substituents R and R are thesame or different lower alkyl radicals such as methyl, ethyl, isopropyl,propyl, butyl, isobutyl, etc.

The literature discloses that partial esters of type (I) can be obtainedwith other reaction products by the Tischenko condensation of analdehyde having a single a-hydrogen atom in the presence of an alkoxidecatalyst: Tischenko et -al., Chem. Zentr., 1906, II, 1552-1556;Kulpinski and Nord, J. Org. Chem., 8, 256 (1943); and Villani and Nord,J. Am. Chem. Soc., 69, 2605 (1947). The reaction can be represented bythe equation:

NaOR BRROHCHO RRCHCH(OH) CRR'CH2O 0C CHRR An improved method ofpreparing the diol half esters (I) is disclosed in the copending vU.S.patent application of H. I. Hagemeyer, Jr., and H. N. Wright, Jr., Ser.No. 122,104, filed July 6, 1961, now US. Patent No. 3,091,- 632. In thismethod an aldehyde of the type,

RRCHCHO is contacted with an alkali metal alkoxide catalyst under dry,acid-free conditions at a temperature of 65 to 105 C., at a low catalystconcentration, preferably less than 2 weight percent, and for a shortresidence time, preferably less than three hours. This procedure can beused to obtain high yields of the desired glycol monoester (I) startingwith aldehydes such as isobutyraldehyde, 2-inethylbutanal, 2-ethylbutanal, 2 methylpentanal, 2 ethylpentanal, 2 ethylhexanal, etc. Inaccordance with the present invention such glycol monoesters areconverted to valuable glycol diesters or polyesters. Thus, a method isprovided for producing esters useful as plasticizers, lubricants,functional fluids, etc., which has an inexpensive branched chainaldehyde as its starting material and thus the method provides importantadvantages of economy over the conventional use of relatively expensiveglycols for preparing esters that are useful as plasticizers andlubricants.

It should be understood that although the glycol monoester product usedas a reactant in accordance with the invention is principally the type(I) monoester having a secondary hydroxyl group in the 3-position, theisomer 3,414,609 Patented Dec. 3, 1968 having the acyloxy group in the3-position and a primary hydroxyl group in the 1-position may also bepresent to a minor extent.

The 2,2,4 trialkyl 3 hydroxypentyl alkanoates can be esterified withcarboxylic acids in the presence of conventional acidic esterificationcatalysts such as hydrochloric acid, sulfuric acid, stannous chlorideand the like and certain novel esters in accordance with the inventioncan be so obtained. However, we have found that when this type of glycolmonoester having a free secondary hydroxyl group is subjected to directesterification or to ester interchange a number of undesirable sidereactions such as dehydration, cyclization and carbonium ionrearrangement can take place in preference to the desired formation ofdiesters or polyesters. The use of conventional esterification catalystssuch as mineral acids, aryl sulfonic acids, titanium alkoxides and zinc,tin and aluminum halides aggravates the tendency of these glycolmonoesters to undergo the undesired side reactions.

We have now discovered that superior results in yield and quality of thedesired esterification product can be obtained by carrying out theesterification of the glycol monoesters of type (I) in the presence ofcertain selected catalysts. These catalysts are substantially neutral orbasic compounds of divalent or tetravalent tin, including tin oxides,tin hydroxides, and certain organo-tin compounds of which thenon-metallic atoms are limited to carbon, hydrogen and oxygen. Theorgano-tin compounds include tin alkoxides and derivatives of tincontaining one or more hydrocarbon radicals, i.e., alkyl, alicyclic oraryl, attached to the tin atom through a direct carbon-tin linkage.Examples of suitable organo-tin compounds in clude diand tetra-alkyl andaryl tin compounds such as dibutyl tin, dihexyl tin, diphenyl tin,dibenzyl tin, tetrabutyl tin, tetraethyl tin, tetramethyl tin, dibutyldiphenyl tin, and tetraphenyl tin; diand tetraalkoxides such as tindibutoxide and tin tetrabutoxide; mixed alkyltin alkoxides such asdibutyl tin dibutoxide; and alkyl tin salts having alkyl and acyloxyradicals attached to the tin atom, such as dibutyl tin diacetate anddibutyl tin di- 2 ethylhexanoate. Also suitable are tin compounds inwhich two of the tetraalkyl radicals are replaced with oxygen to formcompounds such as dimethyl tin oxide, dibutyl tin oxide, diheptyl tinoxide, and dioctyl tin oxide.

The suitable tin catalysts thus include compounds of the types R Sn,R,Sn, Sn(OH) Sn(OH) SnO, SnO Sn(OR) Sn(OR) R SnO, R Sn(OR) and wherein Ris a straight or branched chain alkyl radical of 1 to 8 carbon atoms oran aryl radical of 6 to 9 carbon atoms (e.g., phenyl, tolyl, benzyl,etc.) and Ac is an acyl radical of 2 to 18 carbon atoms (e.g., acetyl,butyryl, stearoyl, benzoyl, etc.).

We have discovered that by the use of such substantially neutral orbasic tin catalysts we can produce esters of the glycol monoesters oftype (I) [and monocarboxylic or dicarboxylic acids with little or nodehydration, cyclization or carbonium ion rearrangement. By reducing orsubstantially eliminating the undesired side reactions we produce thedesired esters and polyesters in markedly improved yields, for example,in yields as high as about percent or even higher. Furthermore, by themethod of our invention we can obtain esters that have little or nocolor or odor, products that are thus quite valuable in certainplasticizer uses.

The acids used as reactants in our process can in gen eral be anyaliphatic, .alicyclic or aromatic monocarboxylic or dicarboxylic acid,including acids having halogen, oxygen, sulfur or nitrogen containingsubstituents that do not interfere with the esterification reaction. Thepreferred acids are aliphatic and aromatic acids having from 2 to 20carbon atoms per molecule.

Examples of suitable mo-nocarboxylic acids include straight or branchedchain, saturated or unsaturated aliphatic acids and aromatic acids suchas acetic acid, propionic acid, butyric acid, isobutyric acid,Z-methylbutyric acid, 3-methylbutyric acid, hexanoic acid,2,2-dimethylbutyric acid, Z-ethylhexanoic acid, 2,2-dimethylhexanoicacid, pelargonic acid, 2,2,4-trimethylpentanoic acid, 2,2,4-trimethylpentanoic acid, 2,2-dimethyloctanoic acid, lauric acid, stearicacid, acrylic acid, methacrylic acid, vinylacetic acid, crotonic acid,oleic acid, benzoic acid, linoleic acid and o-toluic acid. Mixtures ofmonocarboxylic acids can also be used to esterify the glycol monoester.A particularly useful mixture is a mixture of fatty acids derived fromtall oil. Such mixtures are available commercially as fatty acidfractions of tall oil which consist essentially (e.g., 98 to 99 Weightpercent) of fatty acids of from 16 to 20 carbon atoms, of which about 70to 95 percent are unsaturated acids such as oleic and linoleic.

The dicarboxylic acids used in the method of the invention are ingeneral acids of the type, HOOC-RCOOH, wherein R is a divalent organicradical such as a straight or branched chain alkylene or alkenyleneradical of from 1 to 8 carbon atoms; a divalent alicyclic radical; aphenylene radical or substituted phenylene radical preferably of 6 t 9carbon atoms of which the bonds to the carboxyl groups are in the ortho,meta or para position; oxygen or a radical such as R'OR- or R'SR,wherein R is a lower alkylene radical of, for example, 1 to 4 carbonatoms. R can also be simply a bond connecting the carboxyl groups, inwhich case the acid is oxalic acid.

Examples of such dicarboxylic acids include acids of the oxalic acidseries, C H (COOH) wherein n is an integer from 0 to 8 such as oxalicacid, malonic acid, succinic acid, glutaric acid, adipic acid,trimethyladipic acid, 2,2-dimethylglutaric acid, azelaic acid, sebacicacid, etc.; acids of the fumaric acid series, C H (COOH) wherein n is aninteger from 2 to 8, such as maleic acid, fumaric acid, itaconic acid,etc.; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylicacid; aromatic acids, such as phthalic acid, terephthalic acid,isophthalic acid, etc.; acids in which the divalent radical connectingcarboxyl groups containing oxygen or sulfur, such as diglycolic acid,thiodipropionic acid, and the like. When available the correspondingacid anhydrides of the monoor di- R (H) R (f R O I II and 5:2 for themonocarboxylic acid and the dicarboxylic acid, respectively. The tincatalyst of the type described is employed in a concentration preferablyof about 0.001 to 1 percent. Higher concentrations can be used but withno particular advantage. The reaction is carried out at temperaturesranging in general from to 250 C. and at atmospheric pressure, althoughhigher or lower pressure can be used. Inert diluents such as diethylether, diisopropyl ether, ethylene dichloride, benzene, toluene orxylene or other suitable azeotoroping agents can be used to remove thewater as formed and to maintain the desired reaction temperature. Forsuitable reaction rates and for products of the least amount of color wegenerally prefer to operate in the temperature range of 120 to 210 C.

When substantially all of the acid is reacted, the crude ester isstripped with an inert gas such as steam or methane to remove traces oflower boiling materials, washed with dilute alkali to remove residualacidity, dried and filtered to obtain the final product.

In continuous operation of the process it is sometimes desirable tosubject the gross reaction product to an alkali Wash and then to washwith water. The azeotroping agent is stripped out with lower boilingmaterials for recycle t0 the process. The product is then dried andfiltered.

The reaction that takes place when employing a monocarboxylic acid inthe method of the invention can be represented by the followingequation:

wherein R and R are lower alkyl radicals and R" is the residue of analiphatic or aromatic carboxylic acid having from 2 to 20 carbon atoms.

When a dicarboxylic acid is used in accordance with the invention, esterinterchange occurs in addition to direct esterification and the productis at least in part a polyester. The reaction can be represented asfollows:

carboxylic acids can also be used, such as acetic anhydride, isobutyricanhydride, maleic anhydride, phthalic anhydride, succinic anhydride,glutaric anhydride, etc. When our specification and claims refer to theuse of an acid in preparing esters in accordance with the invention Weuse the term acid in its generic sense to mean either the acid or thecorresponding acid anhydride.

In carrying out the method of the invention the monocarboxylic ordicarboxylic acid, and the glycol monoester (I) are mixed and heated ina reaction vessel with the catalysts for a reaction period preferably ofat least about 4 hours or up to about 24 hours. The mole ratio of glycolmonoester to acid can be about 1:1 when using a monocarboxylic acid andabout 2:1 when using a dicarboxylic acid. The use of an excess of theglycol monoester increases the reaction rate. Therefore, preferably theglycol monoester is used in a slight excess of the molar equivalent tothe acid. The preferred mole ratios are about 5:4

wherein R and R are the same as above, R" represents a divalent straightor branched chain, saturated or unsaturated hydrocarbon radical, e.g.,an alkylene or alkenylene radical, of 1 to 10 carbon atoms, a phenyleneor substituted phenylene radical, a divalent alicyclic radical, aradical of the 'type ROR or RS-R, oxygen, or the covalent carbon-carbonbond between the two carboxyl groups of oxalic acid. The value of n isone or greater, e.g., 1 to 10. Preferably, the average molecular weightof the polymeric reaction mixture (ebullioscopic method) is in the rangeof about 500 to about 1500 and therefore the value of n is preferably nogreater than about 5.

Normally the reaction product obtained with dicarboxylic acids comprisesa mixture of esters in which n is from 1 to about 5, the principalcomponent being the compound in which n equals one. For example, in thereaction of 3-hydroxy-2,2,4-trimethylpentyl isobutyrate with adipicacid, the equilibrium composition under the preferred reactionconditions consists of approximately 60 weight percent of the compoundin which n equals one and weight percent of polyesters in which n isgreater than one. It is possible to separate by distillation thematerial with the value of n equal to one (which, for brevity, we canrefer to as the monomer) from the higher polymeric compounds. Theproducts prepared in accordance with the invention can comprise fromabout 25 to weight percent of the polymeric material, the rest beingessentially the monomer. For some purposes either the monomer, themixture as produced in the reaction or the higher polyester (11:2 to 5separated from the monomer will be preferred. We have found that themixtures as produced have exceptional properties as plasticizers andlubri- CH3 E? Boiling range, C., 9 microns Hg -142 Refractive index, nC. 1.4532

Hydrolytic stability, percent saponified at reflux in 0.5 N NaOH:

After 7 hrs 5 After 16 hrs 8 Flash point, open cup, F. 453 Freezingpoint, F. 29 Viscosity, kinematic, cs.:

The product of the above example obtained by esterifieation of TMPD-MIwith adipic acid consisted predominantly of material of the generalformula:

0 CH3 II I cants. As a plasticizer the mixture shows better permanencethan the monomer by itself, although the plasticizer activity of themixture is not quite so good as that of the monomer when equal weightsare compared. When used in a lubricating composition the products of theinvention, particularly the products containing the higher polymericmaterial, are advantageously blended with other lubricant componentssuch as a diester synthetic lubricant of lower molecular weight andlower viscosity than the polymeric material of the invention. Certain ofthe compositions prepared by the method of the invention are also usefulas antioxidant additives for polyolefins or as reagents forcopolymerization with vinyl monomers to form polymeric surface coatingmaterials.

Further understanding of the invention can be obtained from thefollowing working examples which illustrate procedures in accordancewith the invention and other procedures. Certain of the examples alsoillustrate the preparation of novel compositions of the invention.

Example 1 describes the preparation of a novel polyester composition inaccordance with the invention by the reaction of adipic acid with3hydroxy-2,2,4-trimethyl pentyl isobutyrate (the latter also beingcalled 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate and abbreviatedas TMPD-MI). The polyester composition of this example is a valuable newmaterial, being useful, for example, as a synthetic lubricant, as aplasticizer for vinyl resins, cellulose esters and other polymericplastics and for other purposes.

In the examples and tables hereinafter the abbreviation APHA stands forAmerican Public Health Association. The measurements of APHA color, on aPt-Co scale, is described on page 673 of the book Technical Methods ofAnalysis by Roger C. Grifiin, published in 1927 by McGraw-Hill. Theabbreviation ASTM stands for American Society for Testing Materials.

Example 1 A mixture consistingof 292 g. (2 mols) of adipic acid, 1080 g.(5 mols) of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, g. xyleneand 1.6 g. of dibutyl tin oxide was heated to reflux under a waterseparator. The water as formed was removed azeotropically. The basetemperature ranged from 188 to 197 C. Essentially all of the adipic acidhad reacted in seven hours. The mixture was stripped free of low boilerswith low pressure steam superheated to C. and the product washed with 5percent caustic solution. The organic layer was then dried and filteredto give 1039 g. (96 percent yield) of polyester having the followingphysical properties:

Color, APHA, p.p.m. 80 Specific gravity, 20/20 C. 1.0047 Acid number 1.5Molecular weight 625 wherein n is an integer from 1 to 5. This productis useful as a synthetic lubricant. It can be used for instance as amajor or minor component of a synthetic lubricant blend with aconventional diester lubricant. The product is particularly valuable asa plasticizer. It has very low color and is essentially odorless. It iscompatible with polymeric plastics such as cellulose acetate butyrate,ethyl cellulose, cellulose nitrate, phenolic resins and poly(vinylchloride) in resin to plasticizer ratios of 1:1 to 1:4 and with poly-(vinyl acetate) and polystyrene in ratios of 1:3 and 1:4. It is usefulas a permanent-type primary plasticizer for vinyl formulations,especially plastisols. Its excellent hydrolytic stability makes itvaluable as a plasticizer for products used under humid conditions.Although of rather high molecular weight, it is easily handled becauseof low viscosity and low freezing point. The processing of vinyls isaided by its striking in ability. It exhibits good mechanical propertiesand permanence in calendered vinyl film and sheeting and extrudedformulations. The excellent electrical properties, particularly highdielectric strength and volume resistivity, imparted to vinyls by thisplasti cizer is useful in plastics requiring electrical insulatingcharacteristics.

Certain of the valuable properties of the TMPD-MI adipic acid polyesterof Example 1 are shown in Table I which compares the permanence andextraction properties of the polyester of the invention with those ofthe conventional plasticizer di-2-ethy'lhexyl phthalate (abbreviatedDOP) in milled poly(vinyl chloride) formulations.

1 'IMPD-MI=2,2,4-trimethyl-1,B-peutanediol monoisobutyrate.

The product of Example 1 is also useful as a plasticizer forpolypropylene. When milled into polypropylene the resulting resin showsa higher flow rate and a lower brittleness temperature while thestiffness is substantially unaffected. These physical properties ofpolypropylene plasticized with 5 weight percent of the polyester of Examle 1 and of unmodified poly-propylene are given in Table II.

TABLE II Physical Property Plastieized Unmodified PolypropylenePolypropylene Flow Rate at 230 13 5 Brittleness Temperature 16 +20Stiffness m Flexure, p.s.i 114, 700 119, 900

The superiority of our method over the use of other catalysts foresterifying the 2,2,4-trialkyl-3-hydroxypentyl alkanoates isdemonstrated by the next two examples in which a mineral acid andtitanium alkoxide were used as the catalyst and the yield and/ or colorof the product were poor.

Example 2 Example 3 When the reaction described in Example 1 wasrepeated except that 2 g. of titanium tetraisopropoxide was used as thecatalyst, 945 g. (87 percent yield) of product was obtained having anAPHA color of 500.

The next two examples demonstrate the method of the C H; O I

invention using other dicarboxylic acids of the oxalic acid series, C H(COOH) or the anhydride thereof and the preparation of novelcompositions of the invention having utility as synthetic lubricants andas plasticizers for polymeric plastics such as vinyl resins and 3acellulose esters.

Example 4 The procedure of Example 1 was repeated but using 296 g. ofphthalic anhydride (2 mols) instead of adipic acid. A yield of 1080 g.of novel polyester product (95 percent yield) was obtained. The productconsisted predominantly of material of the general formula:

wherein n is an integer from 1 to 5. Typical physical properties of theproduct of this example are as follows:

Color, APHA, p.p.m. 60 Specific gravity, /20 C. 1.0519

Acid number 1.7 Molecular weight 640 Boiling range, C., 15 microns Hg135-200 Refractive index, n C. 1.4877

Example 5 The procedure of Example 1 was repeated but using 376 g. ofazelaic acid (2 mols) instead of adipic acid. A yield of 1132 g. ofnovel polyester product (97 percent yield) was obtained which consistedpredominantly of material of the general formula:

C I13 0 0 H3 0 C 3 (l H-Clla wherein n is an integer from 1 to 5, Theproduct had the following physical properties:

Color, APHA, p.p.m. Specific gravity, 20/20 C. 1.0028

Acid number 1.1 Molecular weight 695 Boiling range, C., 60 microns Hg170-180 Refractive index, n C. 1.4544

The next example demonstrates the method of the invention with anotherglycol monoester having a free secondary hydroxyl group and thepreparation of a novel composition of the invention useful as alubricant and as a plasticizer.

Example 6 The procedure of Example 1 is repeated but using 1290 g. of2,4-dimethyl-2-ethyl-1,3-hexanediol mono-2- methyl'butyrate (5 mols)instead of TMPD-MI. A typical yield of 1180 g. of novel polyesterproduct (94 percent yield) is obtained, which consists predominantly ofmaterial of the following general formula:

wherein n is an integer from 1 to 5. The product has the followingtypical physical properties:

Color, APHA, p.p.m. Acid number 1.0 Molecular weight 670 Boiling range,C., 10 microns Hg 130-155 The next example illustrates theesterification of TMPD-MI with a thiodicarboxylic acid in accordancewith the invention.

Example 7 The procedure of Example 1 was repeated except that 356 g. (2mols) of thiodipropionic acid was used instead of adipic acid. A yieldof 1110 g. (97 percent yield) of polyester was obtained having an APHAcolor of 60 and an average molecular weight of 650. This product wasuseful as an antioxidant for polypropylene.

The next two examples illustrate the use of other tin catalysts inaccordance with the invention.

Example 8 The procedure of Example 1 was repeated except that 1.6 g. ofdibutyl tin diacetate was used as the catalyst instead of dibutyl tinoxide. A yield of 1030 g. (95 percent yield) of polyester substantiallythe same as the product of Example 1 was obtained, the product having anAPHA color of 100.

Example 9 and the recovery of a novel unsaturated polyester.

Example 10 The procedure of Example 1 was repeated except that 196 g. (2mols) of maleic anhydride was used instead of adipic acid. Anunsaturated polyester product was obtained in the amount of 916 g. (95percent yield), the product consisting predominantly of material of thegeneral formula:

tyl isobutyrate, 150 g. of xylene and 1.0 g. of dibutyl tin oxide washeated to reflux under a water separator. The water as formed wasremoved azeotropically. The base temperature of the esterificationreactor ranged from 185-196 C. Essentially all the benzoic acid hadreacted in 30 hours. The mixture was stripped free of low boilers withlow pressure steam superheated to 180 C. and the product washed with 5percent caustic solution. The organic layer was then dried and filteredto give 1200 g. (94 percent yield) of benzoate ester of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, having an APHA color of 50. Thesuperior physical properties of this product over those ofdi-2-ethylhexyl phthalate (abbreviated as DOP) when milled intopolyvinyl chloride resin, are illustrated by the following comparativedata:

wherein n is an integer from 1 to 5. Physical properties of the aboveproduct were as follows:

Color, APHA, p.p.m. 500 Specific gravity, /20 C. 1.022 Acid number 2.5Molecular weight 630 Boiling range, C., 10 microns Hg 100-120 Refractiveindex, n C. 1.4592

The poor color of the product was due to the fact that commerciallyavailable maleic anhydride was used in the reaction without priorpurification. A product of much better color can be obtained by usingpurified maleic anhydnde.

The novel unsaturated polyester product of Example 10 prepared by theesterification of TMPD-MI' with maleic acid, in addition to its utilityas a lubricant and as a plasticizer, is also useful in the preparationof useful plastics by copolymerization with a vinyl monomer. Forexample, the unsaturated polyester is mixed with styrene in a parts byweight ratio of about 3:2 and in the presence of a small amount of anorganic peroxide catalyst, e.g., 0.0025 part of benzoyl peroxide. Whenthe mixture is cast on glass plates and cured at elevated temperature,e.g., 80 C. for 4 hours, a hard transparent film is obtained which isuseful as a surface coating.

The next example illustrates use of the method of the invention inesterifying TMPD-MI with a monocarboxylic acid ester, namely benzoicacid. The resulting TMPD-MI benzoate is a valuable plasticizer for vinylfloor tiles. It has excellent compatibility with the usual inorganicfillers for vinyl tile compositions and the tiles have excellentresistance to staining by common household chemicals.

Example 11 A mixture consisting of 488 g. (4 mols) of benzoic acid, 1080g. (5 mols) of 3-hydroxy-2,2,4-trimethylpen- Example 12 When theprocedure of Example 11 was repeated, using 2 g. of sulfuric acid, only428 g. (33.5 percent yield) of benzoate ester was obtained (APHA colorgreater than 500). High amounts of by-products 2,2,4,4-tetramethyltetrahydrofuran (19 percent yield); 2,5-dimethyl-2,4-hexadiene (4 percent yield); and 2,2,4-trimethyl-3-pentenylisobutyrate (39 percent yield) were formed.

A number of additional esters have been prepared in accordance with theinvention from different monocarboxylic acids and two different glycolmonoesters, namely, 2,2,4-trimethyl-1,3-pentanediol monoiso butyrate and2,4- di-methyl-Z-ethyl-1,3-hexanediol mono-2-methylbutyrate. Theprocedure was as follows.

Examples 11341 The esters were prepared by refluxing a mixtureconsisting of 4 mols of the monocarboxylic acid, 5 mols of the glycolmonoester, an azeotroping agent and the tin catalyst. The concentrationof catalyst was 0.2 percent based on the weight of monocarboxylic acidused. The reaction mixture was stripped free of low boilers with steamand the product washed with 5 percent caustic solution. The organiclayer was then dried and filtered to obtain the desired ester. TablesIII and IV below list the particular reactants, reaction conditions andproduct yields for each preparation. The acid identified as tall oilacid was a commercial fatty acid fraction of tall oil comprising atleast about 97 weight percent G -C fatty acids, at least about 70percent being unsaturated acids, about an percent being oleic acid.

TABLE III.-ESTERS OF 2,2,4-TRIMETHYL-1,3-PENTANEDIOL MONOISOBUTYRATE ANDMONOCARBOX- YLIC ACIDS Azeotroping Reaction Reaction Yield Example No.Monocarboxyllc Acid Catalyst Agent ernp Time (percent) 0.) (hrs) 13Acetic Dibutyl tin oxide Benzene 94 14, Propionid do do. 8 93 15.Butyric Stannous hydroxide do 10 95 16 Is0butyr1c Dibutyl tin oxide do16 92 17s Z-methylbutyrrc. "do do 18 94 18. 3-mcthylbutyric. Stannoushydroxide do 16 93 19. Hexanoic Dibutyl tin oxide do 9 98 202,2-dirnethylbutyuc Dibutyl tiu diacotate "do" 18 91 21.2-ethylhexanoic. Dibutyl tin oxide Xylcne 16 94 22. 2,2-dimethylhexano1c.do .do. 16 91 23 2,2,-trimethylpentanoic Dibutyl tin dibutoxide "do" 2494 24 2,3,4-trirnethylpentanoic. Dibutyl tin oxide do 24 92 25...2,2-dimethy1octanoic-. do do 22 92 26 Tall oil acid do do 18 96 TABLEIV.ESTERS OF 2,4-DIl\lETI-IYL-2-ETHYL-L3-HEXANEDIOLMONO-Z-METHYLBUTYRATE AND MONOCARBOXYLIC ACIDS Azeotroping ReactionReaction Yield Example No. Monocarboxyhc Acid Catalyst Agent Temp. Time(percent) 0.) (hrs.)

27 Acetic Stannous hydroxide Benzene 155165 8 94 28 Propionic. Dibutyltin diacetate. 150165 8 93 29 Butyric- 12 92 30 Isobuty1ic 16 93 312-methylbutyr1c 18 94 32". 3methylbutyric 16 91 33. Hexanoim 10 96 342-ethylhexanoio Stannous hydroxide 18 94 35m 2,2-dimethylbutyri Dibutyltin di-2-ethylhexanoate Benzene 20 94 36 2,2-dnnethylhexano1c Dibutyltin oxide r. Xylene 180-200 18 95 37... 2, ,4-trimethylpentauo1c- 0 do180-200 24 93 38 2,3,4-trimethy1pentanoic ..do do" 180-200 22 95 392,2-dimethyloctanoic. Staunous hydroxide do. 180-200 24 91 BenzoicDibutyl tin diacetate do 180200 30 93 41 Tall oil acid Dibutyl tin oxide-do 180200 18 95 The next example describes the preparation of a novelpolyster of the invention which has unexpectedly valuable properties asa plasticizer.

Example 42 The procedure of Example 1 was repeated but using 268 g. ofdiglycolic acid (2 mols) instead of adipic acid. A yield of 98 6 g. ofpolyster product (93 percent yield) was obtained which consistedessentially of material of the general formula:

CH3 0 CH3 wherein n is an integer from 1 to 5. Typical properties of thenovel TMPDMI diglycolate as prepared in this example are as follows:

Color, Gardner scale 3 Specific gravity, 20/20 C. 1.025 Pounds pergallon, 20 C. 8.5 Acid number 1.1 Boiling range, C., 15 microns Hg -l5Freezing point, F. 15 Flash point, Cleveland open cup, F. 383 Molecularweight 610 The novel TMPDMI diglycolate polyester as prepared in Example42 is useful as a lubricant and as a plasticizer. It is compatible as aplasticizer with a wide range of polymeric plastics including vinylresins, cellulosics, phenolic, alkyd and acrylic resins and nitrilerubber. It is particularly useful as a plasticizer for acrylic lacquersin which use it shows excellent retention properties and improvement inthe elongation tests of the lacquer film.

From the foregoing specification it will be seen that we have developeda novel process for producing useful mixed diesters and polyesters ofglycol monoesters having a free secondary hydroxyl group, our processbeing based on the discovery that certain selected tin compoundscatalyze the desired esterification reaction without producing largeamounts of various undesired by-products that are obtained with otheresterification catalysts. The specification further ShOWS that we haveproduced certain novel polyesters of 3-hydroxy-2,2,4-trimethylpentylisobutyrate and dicarboxylic acids, which polyesters are useful aslubricants and as plasticizers and in such uses possess one or more of anumber of unexpected properties of considerable value such as hydrolyticand thermal stability, excellent retention properties, plasticizercompatibility C Ha O C Ha with a wide range of resins, and the abilityto blend with synthetic resins to form plastic compositions of markedlyimproved flexibility, elongation, resistance to staining and the like.

Although the use of certain organo-tin compounds as esterificationcatalysts has been disclosed in British Patent 810,381, there hasapparently been no prior disclosure or use of the neutral to basic tincompounds as catalysts for estcrifying the glycol monoestcrs describedherein and no prior recognition of the unexpected advantages that aregained from this novel combination. Thus, whereas British Patent 810,381apparently treats all organo tin compounds as equivalents, includingcertain halogenated tin compounds, and deals with the esterification ofnonesterified hydroxyl compounds, we have found that the neutral tobasic tin catalysts are uniquely adapted for esterification of glycolmonoesters of the type of 2,2,4- trimethylpentane-l,3-diolmonoisobutyrate and its homologs. The latter type of glycol monoesterbeing characterized by the so-called neo or 2,2-dimethyl structure, ishighly susceptible to molecular rearrangement. It appears that theneutral to basic tin catalysts are uniquely adapted to esterify suchglycol monoesters with the minimum of molecular rearrangement,dehydration and other reactions yielding highly colored or otherwiseundesired rel3 14 action products. Furthermore, it appears that theglycol prepared by esterifying 2,2,4-trimethyl-l,3-pentanediol monoesteris unexpectedly superior to the corresponding monoisobutyrate with aphthalic acid. glycol in its resistance to rearrangement, thusindicating 4. The product of claim 1 wherein R and R are methyl that theuse of the particular type of glycol monoester and R is (CH said producthaving been prewith the neutral or basic tin catalysts is a combination5 pared by esterifying 2,2,4 trimethyl 1,3 pentanediol that contributesto stability against undesired molecular monoisobutyrate with azelaicacid. rearrangement of the neo compound. 5. The product of claim 1wherein R is methyl, R The invention has been described in considerabledeis ethyl and R is -(CH said product having been tail with particularreference to certain preferred embodirepared by esterifying2,4-dimethyl-2-ethyl-1,3-hexanements thereof, but it will be understoodthat variations 10 diol mono-2-methylbutyrate with adipic acid. andmodifications can be effected within the spirit and 6. The product ofclaim 1 wherein R and R are methyl scope of the invention as describedhereinabove, and as and R is -CH=CH--, said product having beenpredefined in the appended claims. pared by esterifying 2,2,4 trimethyl1,3 pentanediol We claim: monoisobutyrate with maleic acid. 1. Theproduct having the formula: 7. The product of claim 1 wherein R and Rare methyl W V m 5% m R-CH-O-O-CHa-C-OHOCR-COCHCCH:-O J( JHR wherein Rand R are lower alkyl radicals and R is seand R" is --CH OCH saidproduct having been lected from the group consisting of: alkylene,alkenylene repared by esterifying 2,2,4 trimethyl 1,3 pentanediol andcycloalkylene radicals of 1-8 carbon atoms; arylene monoisobutyrate withdiglycolic acid. radicals of the benzene series containing 6-9 carbonatoms; the radicals RSR- and 20 References Cited m m UNITED STATESPATENTS 3,160,59 1964 wherein R' is a lower alkylene radical; and thecarbon- 3 211 15 22 32; et a1 carbon bond of oxalic acid; and wherein nis an integer 3O 2720507 10/1955 Caldwell from 1 to 5.

2. The product of claim 1 wherein R and R are methyl FOREIGN PATENTS andR is (CH said product having been prepared by esterifying 2,2,4trimethyl 1,3 pentanediol monoisobutyrate with adipic acid.

3. The product of claim 1 wherein R and R are methyl LORRAINE WEINBERGERPrimary E and R" is a phenylene radical, said product having been T. L.GALLOWAY, Assistant Examiner.

810,381 3/1959 Great Britain.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,414,609 December 3, 1968 Hugh J. Hagemeyer, Jr. et al.

It is certified that error appears in the above identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 7, the formula at the bottom of the page should appear as shownbelow:

CH3 0 (I31 o 0 CH3 0 CH3 c11 cH!-ocH -ccHo l (CH2) 7-C-O-iH-C-CHg-Olia-cs CH3 CH-CH3 CH3-CH CH3 n CH3 CH3 Column 9, Example 10, lines 28 to38, the formula should appear as shown below:

CH3 0 CH3 CH3 0 0 CH3 CH3 OCH3 luvlfl I CH3CHCHCOCHQC-CIHOCCH=CHC-OClHC-CH2O C'CHCH3 cn clrn CH CiH n CH CH Column 14, line 4, (CHshould read (CH Signed and sealed this 10th day of March 1970.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR Attesting OfficerConunissioner of Patents

1. THE PRODUCT HAVING THE FORMULA: